1. Field of the Invention
The present invention relates to a bearing structure including an oil-impregnated bearing including a porous sintered metal material and an air blower having the bearing structure.
2. Description of the Related Art
For example, JP-B-4596613 discloses a technique of collecting and returning a lubricant leaking from an oil-impregnated bearing in a bearing structure including the oil-impregnated bearing made of a porous sintered metal material. In the bearing structure described in Japanese Patent No. 4596613, since an opening of a sleeve holder (bearing holder) is not sealed, foreign substance may go into the sleeve holder from the opening, particularly, between the oil-impregnated bearing and a shaft body. In a bearing unit (bearing structure) described in JP-A-2009-063094, leakage of a lubricant is prevented by sealing an opening edge of a housing (bearing holder) with a seal member. However, since a porous elastic material (such as felt or sponge) received in the seal member is brought into close contact with an end face of a radial bearing (oil-impregnated bearing), that is, since two members of a member for sealing and a member for holding a lubricant are required, there is a problem in that the number of components (members) increases.
JP-A-2001-271828 discloses a dynamic pressure type sintered oil-impregnated bearing unit (bearing structure) in which an opening of a housing (bearing holder) is sealed with a seal member including a single sintered metal material. For example, when the seal member made of the sintered metal which is used in the bearing unit described in JP-A-2001-271828 is applied to the bearing unit described in JP-A-2009-063094, an increase in the number of components can be prevented, but, similarly to the bearing structure described in JP-B-4596613, foreign substance may come in from a clearance provided between a side wall of the radial bearing (bearing holder) and an outer surface of a shaft in the bearing unit described in JP-A-2009-063094.